The present invention relates generally to material transportation. More particularly, the present invention relates to capsulate-type material conveying in a pipeline.
For many years it has been known that fluid could be efficiently transferred by the use of pipelines. A fluid would be introduced into one end of a pipeline, pressure would be applied by means of pumps or gravity and the fluid would flow along the length of the pipeline to a desired destination.
Solids may be transported by pipeline if the solids are first ground or crushed and then mixed with a suitable liquid to form a slurry. The slurry may be pumped through a pipeline, although the particles of solid within the slurry introduce additional problems in the apparatus required to pump and transport such material.
Most recently it has been discovered that there may be some energy efficiency in introducing the material to be transported into a capsule and then transporting the capsule through a pipeline. Systems exist whereby packaged or bulk material is introduced into wheeled capsules which are propelled through a pipeline by columns of air. Typically trains of, say, three or four capsules are formed and then transported through the pipeline by columns or "slugs" of air moving at or near atmospheric pressure.
Two-directional flow is achieved through the use of a closed-loop system. Such a system could, of course, form a circle, or the like, with several terminals. Alternatively, a double pipeline could be built between two primary terminals with one pipeline representing a forward path and the other representing a return path. At each terminal a bypass system may be utilized to prevent the flowing air or fluid from being interrupted at terminals or stations.
The speed and grade-climbing ability of capsules in such a system have been limited in the past by a variety of factors, including pump capacity. It is believed that with known systems, extraordinarily large pump volumes are required to achieve economically suitable speeds and carrying capacities of capsules in a pipeline. It is believed that the energy requirements to move suitable volumes at acceptable speeds result in the consumption of an economically unfeasible quantity of energy.
It is further believed that in systems which rely on a continuous downstream flow of gas in a pipeline to convey pipeline capsules, not only are large volumes of gas flow required, but also high gas flow rates to provide a sufficient driving force for driving capsules along the pipeline. However, such a high volume, high flow rate gas flow will be subject to substantial frictional losses along the length of the pipeline.
Because of the high losses, it is frequently necessary to boost the gas flow rate at spaced intervals along the pipeline. This is usually done by extracting a fraction of the gas flowing down the pipeline, substantially increasing the pressure of the extracted fraction, and then reintroducing it substantially axially into the pipeline.
Because only a fraction of the gas flowing along the pipeline is extracted and pressurized, substantial pressures are required to boost the gas flow rate in the pipeline sufficiently to continue conveying the capsules.
It is further believed that in such systems the energy transfer from the gas streams to capsules in the pipeline, is essentially in the form of kinetic energy which will have the effect of momentarily accelerating a capsule, followed by gradual deceleration as the gas flow rate along the pipeline decreases.
Therefore, it is an object of the present invention to provide novel method and apparatus for conveying material in pipeline capsules which minimizes the factors which limit the speed and capacity of pipeline systems in the prior art.
In accordance with one embodiment of the invention a method and apparatus for conveying solid or fluid material in a pipeline capsule includes a series of pumping stations positioned along the length of a capsule-carrying pipeline. The pipeline is filled with a continuous link of capsules. It is believed that the "slugs" of air which prior art arrangements utilized to separate small trains of capsules created an undersirable amount of turbulence which resulted in significant energy losses.
At each station the pipeline passes through an enlarged diameter energy transfer station, zone or enclosure with slots or the like being placed in the pipeline to place the pipeline in fluid communication with the interior of the enlarged diameter zone. Three manifolds are provided: one at an upstream location in the pipeline; a second, near the entrance of the large diameter zone; and a third near the exit of the large diameter zone.
A first pump or compressor is arranged to pump, say, air or other suitable fluid from the third manifold toward the second manifold. A second pump or compressor is arranged to pump air from the first manifold to the second manifold. The arrangement of pumps provides a region or zone of highest pressure in the entrance to the enlarged diameter zone, a zone of intermediate pressure near the exit of the enlarged diameter zone, and a region of yet lower pressure in the vicinity of the first manifold.
Further according to the invention there is a provided a pipeline capsule transportation apparatus for transporting capsules in a continuous linked train, the apparatus comprising:
(a) an elongated pipeline having an upstream pipeline location and a downstream pipeline location, PA1 (b) an energy transfer station downstream of the downstream pipeline location, the transfer station comprising an elongated enclosure which is associated with a length of pipeline and is in fluid communication with the length of pipeline, the enclosure having a cross-sectional area larger than that of the pipeline, PA1 (c) station pump means for withdrawing fluid from a downstream location of the station and pumping the fluid into an upstream location of the station to provide downstream fluid flow along the enclosure for propelling capsules passing through the length of pipeline in the enclosure, and PA1 (d) control means for controlling the velocity of fluid between the upstream and downstream pipeline locations during use for the pressure to be less at the upstream pipeline location than at the downstream location, and for the pressure at the downstream station location to be greater than the pressure at the upstream pipeline location.
The enclosure may conveniently be in communication with the length of pipeline within the enclosure, substantially along the entire length of that length of pipeline.
In an embodiment of the invention the control means may comprise pipeline pump means to withdraw fluid from the upstream pipeline location.
The pipeline may conveniently comprise a plurality of successive sections, with each section comprising an elongated pipeline having pipeline pump means at an upstream location and having an energy transfer station downstream of a downstream pipeline location.
In an alternative embodiment of the invention the control means may comprise an expansion chamber extending between the upstream and downstream pipeline locations, the chamber being in communication with the pipeline and in communication with the enclosure of the energy transfer station.
It would be appreciated that, in this embodiment of the invention, the pipeline would have an elongated length of pipeline upstream of the upstream pipeline location.
In this embodiment of the invention the pipeline may again comprise a plurality of successive sections, with each section comprising a length of pipeline having an expansion chamber at a downstream location, and having an energy transfer station downstream of the expansion chamber and in communication therewith.
The pipeline may, for example, be in the form of an endless loop.
The invention further extends to a pipeline as described, including a continuous train of linked capusles in the pipeline.
Further in accordance with the invention, a method of transporting capsules along a elongated pipeline, includes the steps of displacing the capsules as a continuous linked train of capsules in the pipeline by controlling fluid velocity in the pipeline between an upstream pipeline location and a downstream pipeline location to maintain a pressure which is lower at the upstream location than at the downstream location, and by maintaining downstream of the downstream pipeline location a flow of fluid downstream in an enclosure which is associated with a length of the pipeline and is in fluid communication with the length of pipeline, the flow of fluid being maintained by withdrawing fluid from an exit region of the enclosure and pumping the fluid into an entrance region of the enclosure, and the flow of fluid being maintained to provide a pressure at the entrance region which is greater than the pressure at the exit region, and a pressure at the exit region which is greater than the pressure at the upstream pipeline location.
The fluid velocity between the upstream and downstream pipeline locations may again be controlled in the manner as hereinbefore described.
In an embodiment of the invention the method may include the steps of continuously feeding capsules into an inlet end of the pipeline, linking the capsules, and continuously discharging capsules from a downstream discharge location.
Examples of the more important features of this invention have thus been summarized rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will also form the subject of the claims appended hereto. Other features and advantages will become apparent with reference to the following description and accompanying drawings.